Sirman E7

What does Sirman E7 mean?

The PLD 300-330-350 AUT control system is measuring a DC bus voltage that has fallen below the minimum acceptable threshold required for safe motor operation. The drive is detecting an under-voltage condition on the internal DC bus, which is directly derived from the incoming mains supply. Per Sirman's manual, the primary diagnostic action is to verify that the power supply voltage at the machine's connection point is correct and stable.

Symptoms

• Display shows 'E7' and the machine refuses to start or stops during operation.
• Machine performance is sluggish or motor runs slower than expected before faulting.
• Fault occurs consistently, particularly when other high-draw equipment is running on the same circuit.
• Lights or other equipment on the same circuit appear dimmer than normal.
• Fault may appear intermittently in correlation with peak-demand periods.

Common causes

• Incoming mains supply voltage is too low or outside the rated voltage range for the PLD model.
• Excessive voltage drop caused by undersized or damaged supply cabling to the machine.
• Shared circuit overloaded by other equipment drawing the supply voltage down.
• Loose or corroded connections at the wall outlet, plug, or machine terminal block increasing resistance.
• Facility supply instability or brownout conditions from the utility provider.
• Failed or degraded internal rectifier or filter capacitors on the power board causing low bus voltage even with adequate mains input.

Diagnostic steps

1. 01

   Measure incoming mains voltage

   Using a calibrated multimeter, measure the voltage at the wall outlet or terminal supplying the machine. Confirm it matches the rated supply voltage specified on the Sirman PLD 300-330-350 AUT nameplate.

2. 02

   Check voltage under load

   Measure the supply voltage again while the machine is attempting to run to detect dynamic voltage drop. A significant drop under load indicates supply or wiring inadequacy.

3. 03

   Inspect supply connections

   Examine the plug, socket, and any terminal block connections for looseness, corrosion, or heat damage. Tighten or replace any suspect connections, as high-resistance joints cause localized voltage drop.

4. 04

   Isolate the circuit

   Temporarily remove other high-power equipment from the same circuit and retest the Sirman PLD. If E7 clears, the circuit is overloaded and a dedicated supply circuit should be installed.

5. 05

   Verify supply cable sizing

   Confirm that the supply cable cross-section meets Sirman's installation requirements for the PLD 300-330-350 AUT. Undersized cabling causes excessive voltage drop; replace with correctly rated cable if needed.

When to call a professional

Escalate to a licensed electrician or Sirman-authorised technician if the mains supply voltage is confirmed correct at the outlet but E7 persists, as this may indicate an internal power board fault such as failed rectifier diodes or filter capacitors. Any work involving rewiring, circuit upgrades, or internal drive component replacement must be performed by a qualified professional to comply with electrical safety regulations.